Drafting apparatus

ABSTRACT

A device for attachment to a drafting board which is movable between horizontal and upright positions. The device includes an X-bar and a Y-bar carrying respective carriages to facilitate plotting points on the board with reference to a zero coordinate. When the board is tilted a removable balance weight is added to compensate for the weight of the moving parts.

[56] References Cited FOREIGN PATENTS OR APPLlCATlONS 787,618 6/1968 Canada........... 6,705,263 10/1968 Nether1ands.... 1,233,749 2/1967 Primary Examiner-Harry N, Haroian Attorney-Bacon & Thomas [57] ABSTRACT A device for attachment to a drafting board which is movable between horizontal and upright positions. The device includes an X-bar and a Y-bar carrying respective carriages to facilitate plotting points on the board with reference to a zero co-ordinate. When the board is tilted a removable balance weight is added to compensate for the weight of the moving parts. i

2 Claims, 1 Drawing Figure Nestler GmbH,

...B43l 13/02 ...33/76 R, 79 R, 79 D, 33/80, 81

United States Patent [191 Gornowi 541 DRAFTING APPARATUS n l 1 l 5 r1.

w a A AQ/ I Ii IZ,: .Z II .IIZZIliII IIIlII/lllllllll This invention relates to drafting apparatus and more particularly to a device for attachment to a drafting board for use with the board in both horizontal and inclined positions.

There are presently two distinct types of drafting apparatus inuse. Firstly, there is a type which can be inclined to the horizontal so that the user stands or sits before a board to make a drawing. Drafting apparatus of this type is commonly called a drafting machine. Secondly, there is a type which is used in civil engineering work and cartography. This type has a board fixed in a horizontal position and has X and Y-co-ordinate scales for plotting positions on a drawing. Such a type of drafting apparatus is known as a co-ordinatograph.

With the advent of computerized drafting apparatus and computerized machine tools, there is a need for drafting apparatus which is suitable for making engineering drawings in relation to a zero coordinate. Although such drawings can be started on a co-ordinatograph, they must be transferred to a conventional drafting machine for completion. This results in many drafting rooms including both types of drafting apparatus with resulting waste of capital investment and in particular a waste of space because the co-ordinatographs require a large floor area.

It has recently been proposed that tiltable drafting apparatus be provided which incorporates advantages of drafting machines and co-ordinatographs in one table. Because the apparatus includes a board which can be used in a generally upright position, it is necessary to provide a balance weight to compensate for the weight of a drafting head and associated carriage. If the board is to be used in a horizontal position, the balance weight is no longer needed and it simply adds to the inertial of the carriage and drafting head when the user moves the head from one position to another.

It is therefore an object of the present invention to provide a device for attachment to a drafting board, the device including a counter balance assembly and suitable for attachment to tiltable drafting apparatus in which the board to be used in inclined positions, the counter balance assembly being attached in such a manner that it is readily removable when the board is in the horizontal position and no counter balance is required.

It is a further object of the present invention to provide a combination drafting machine and co-ordinatograph having a releasable counter balance assembly for attachment when the tiltable board is to be used in an inclined position.

Accordingly, the present invention provides a device for attachment to a drafting board which is movable between horizontal and upright positions. The device includes an X-bar for attachment to the top of the board and extending generally horizontally along the board, and a Y-bar at right angles to the X-bar, the upper end of the Y-bar being attached to an X-carriage running on the X-bar for movement of the Y-bar in an X-direction. A Y-carriage is mounted on the Y-bar for movement in a Y-direction and means are provided on the Y-carriage for attachment of a drafting head and the like. The device further comprises a counter balance assembly releasably coupled to the Y-bar and including a cable, and a weight attached to the cable and slidable on a counter balance bar. The cable can be locked to the Y-carriage so that the counter balance weight compensates for the weight of the Y-carriage and the drafting head.

The invention will be better understood with reference to the drawing FIG. 1 which shows a plan view of tiltable drafting apparatus according to the invention with a board 10 in a horizontal position and mounted on a base assembly 12 having a foot release 14 for tilting the board 10 between horizontal and.

upright positions. A device 15 is attached to the board and includes and X-bar 16 attached to the top of the board 10 for guiding and X-carriage 18. A Y-bar 20 is attached at one of its ends to the X-carriage and extends at right angles to the X-bar and a' Y-carriage 22 is adjustably mounted on the Y-bar 20 and carries a drafting head or other attachment 24. The carriages 18, 22 permit movement of the attachment 24 across the board and respective X-scale and Y-scale 28 permit the user to plot points across the board in relation to an arbitrary zero co-ordinate. To this end, respective scale reading devices 30, 32 are provided on the carriages 18, 22.

Carriage 18 defines a threaded opening 34 at an end adjacent the Y-bar 20 which terminates at its distal end in a pair of threaded openings 36. A threaded opening 38 is also provided in the Y-carriage 22. Respective screws 40, 42 and 44 are provided for engagement into threaded openings 34, 36 and 38 to attach a counter balance assembly 46. The screws have knurled heads for hand release.

The assembly 46 consists of a beam 48 which when assembled extends in a generally parallel relationship with the Y-bar 20. A weight 50 is slidably engaged on the beam 48 for longitudinal movement in a Y direction and is attached by screws 52 or any other convenient means to ends of a cable 54. Respective upper and lower pulley wheels 56, 58 are provided for engaging the cable 54 which extends between the pulley wheels and carries a connecting piece 60 in which screw 44 is engaged loosely. Respective upper and lower brackets 62, 64 are attached to ends of the beam 48 and are drilled for engagement of respective screws 40, 42.

If the board 10 is to be used in an inclined position, then the counter balance assembly 46 is attached by first engaging screws 40, 42 in respective threaded openings 34, 36 and then engaging screw 44 in threaded opening 38 of carriage 22. Then, when the carriage 22 is moved along the Y-axis, the cable 54 transmits motion to the counter balance weight 50 and cable 54 moves around the pulley wheels 56, 58. When the carriage 22 is stopped on the Y-axis, the weight 50 is sufficient to prevent the carriage from moving under the influence of gravity.

The attachment 24 is exemplary of a number of different attachments which will vary in weight relative to attachment 24. For this reason, the counter balance weight '50 is threaded at two openings 66 to receive screws 68 for attaching plates 70 to increase the magnitude of the counter balance weight 50. In practice, the weight 50 is matched to the weight of the carriage 22 together with the lightest attachment and then sufficient plates 70 are provided to increase the weight 50 to balance the heaviest attachment.

I claim:

l v 1. A device for measuring coordinates or for drafting according to coordinates, the device comprising:

a horizontal X-bar for mounting on the top of a draft ing board, the board being tiltable about a horizontal axis;

a X-carriage movably mounted on the X-bar;

a Y -bar attached to said X-carriage and extending substantially at right angles to said X-bar;

a Y-carriage movably mounted on said Y-bar and adapted to releasably receive head attachments for use in measuring, and drafting; and

a removable counter-balance assembly coupled to said Y-bar for movement therewith, said counterbalance assembly comprising: a counter-balance bar; means for removably coupling said bar to said Y-bar in substantially parallel relationship therewith; a weight slidably engaged on said 2. A devic counter-balance assembly further comprises at least one removable member and means releasably attaching the member to the counter-balance weight. 

1. A device for measuring coordinates or for drafting according to coordinates, the device comprising: a horizontal X-bar for mounting on the top of a drafting board, the board being tiltable about a horizontal axis; a X-carriage movably mounted on the X-bar; a Y-bar attached to said X-carriage and extending substantially at right angles to said X-bar; a Y-carriage movably mounted on said Y-bar and adapted to releasably receive head attachments for use in measuring, and drafting; and a removable counter-balance assembly coupled to said Y-bar for movement therewith, said counter-balance assembly comprising: a counter-balance bar; means for removably coupling said bar to said Y-bar in substantially parallel relationship therewith; a weight slidably engaged on said counter-balance bar; a pair of pulley wheels at the ends of said counter-balance bar; an endless closed cable extending over said pulley wheels, said counter-balance weight being connected to said cable at one side of said pulley wheels; a connecting piece fastened to said cable at the other side of said pulley wheels such that upon moving the cable over said pulley wheels said weight and said connecting piece move in opposite directions; and means for removably coupling said connecting piece to said Y-carriage.
 2. A device as claimed in claim 1 in which the counter-balance assembly further comprises at least one removable member and means releasably attaching the member to the counter-balance weight. 